600mA is pretty bold! But I agree with the above posts, a simple LM317 Driver works fantastically! you'd need a 2.08 ohm resistor. But if you found a 2.1 ohm it would run just a little under the 600mA mark. But again, 600mA is playing with fire (or photons) pretty dangerously for a red laser diode.... unless its 635nm
Absolutely! I have a build using 2 14500 batteries and an LM317 and I haven't had to recharge it yet (although I haven't put TOO much time into using it... maybe 30-40 minutes tops)